Can't Edit in Sculpt Mode After Un-Hiding Parts of Mesh in Edit Mode
It's the Mirror modifier that causes the glitch in Sculpt mode. Have a look at the modifier panel and you will see a warning message: &quot;Sculpt: Hide, Mask and optimized display are disabled&quot;. That means the body is hidden but because hide does not work you still see it. A Fatamorgana ;-)
Press the little monitor icon &quot;Realtime&quot; right next to the Mirror modifier's name (in the modifier panel) to disable it in Sculpt mode and you will see what Blender sees. It's only the left hand visible.
Solution: In Sculpt mode, press Alt + H to unhide the hidden body.